Bacteria Produce Distinct Form of Reduced Uranium
Some gram-negative microorganisms are known to reduce soluble uranium to insoluble uraninite [UO2(s)] forming the basis for in situ bioremediation or natural attenuation techniques for uranium in contaminated groundwater. But do all bacteria produce the same forms of reduced uranium? New results indicate that some gram-positive bacteria such as Desulfitobacteria, common to subsurface environments, also reduce soluble uranium but produce a mononuclear uranium species that differs from the commonly observed uraninite mineral form produced by gram-negative bacteria. Researchers from the Georgia Institute of Technology and Argonne National Laboratory working at the Advanced Photon Source (APS) show that Desulfitobacteria produce a form of reduced uranium that is likely coordinated with light atom shells such as C/N/O or S/P rather than the commonly observed uraninite mineral structure [UO2(s)]. The chemical identity of uranium species in subsurface environments is crucial to modeling the biogeochemical processes controlling contaminant transport at DOE sites. These results suggest that these alternate forms of reduced uranium also need to be characterized to be able to accurately predict uranium mobility/stability in reduced environments.
KE Fletcher, MI Boyanov, SH Thomas, Q. Wu, KM Kemner, FE Loeffler, (2010) Environ. Sci. Technol., 44(12): 4705-4709